This invention relates to a laminated iron core for rotary electromachines, and particularly to a laminated iron core for rotary electromachines which has improved thermal and mechanical strength.
Laminated iron cores of the class are exposed to substantial vibration and impact in the course of operation of the rotary electromachines and therefore are required to have their laminar metallic plates firmly bonded to each other. Moreover, the laminated iron cores are placed under severe thermal conditions during the operation, and accordingly must have a sufficient thermal resistance as well as mechanical strength. It has been known as advantageous in the light of the thermal resistance to bond laminar metallic plates with glass material, because the bonding glass material may resist against deterioration or fluidization under heat generated by the operating electromachines. Glass material has the disadvantage that it inherently is not sufficiently strong or tough against mechanical and thermal impact.
In stator iron cores of rotary electromachines where a coolant fluid is introduced in the stator devices for cooling the latter, the laminar metallic plates may be bonded with and the stator devices may be hermetically sealed with glass material so as to provide to the passageways of coolant fluid a seal which is not subject to deterioration or fluidization under heat, unlike a synthetic resin sealant applied for that purpose. Such a synthetic resin sealant is likely to be fluidized under heat, resulting in loss of hermetic seal of the laminated iron core stator devices. Glass material can be applied to the stator iron cores of such stator-cooled rotary electromachines for their hermetic bonding, avoiding the problem encountered by application of the synthetic resin sealant. But the other problem which is ascribed to an insufficient thermal and mechanical impact strength inherently of glass material, remains unsolved, the problem that hermetic seal of glass material may be broken by thermal and mechanical impact during operation of rotary electromachines, leading to the fatal hindrance of the electromachines that the coolant fluid is leaked from the stator devices to the rotor side.
A further problem has been likely to be encountered in manufacture of laminated stator iron cores sealed with a glass material layer when a glass material is applied onto and fused by heat for the purpose on that end face portion of the laminar metallic plates of the semi-finished stator iron cores which defines an air gap relative to the opposed periphery of the rotor as assembled with the finished core subsequently in manufacture of rotary electromachines (hereinafter called "air-gap surface" for brevity). The fused material is likely to flow into or penetrate capillary spaces between the laminar metallic plates so as to be left on the air-gap surface in an insufficient amount which cannot form a durable sealant glass layer of continuity or thickness to the purpose.